In general, as a treatment for a cerebral aneurysm, a clipping operation is performed as shown in FIG. 11. In this clipping operation, upstream from an aneurysm 100, a clip 101 is attached to a cerebral artery 102 so that the flow of blood can once be stopped in the cerebral artery 102. In this state, a clip 103 is attached to the root of the aneurysm 100. This prevents blood from flowing into the aneurysm 100, thereby evading a rupture of the aneurysm 100.
After this process has been completed, the clip 101 is detached so that the flow of blood can be recovered in the cerebral artery 102. Then, the incised head part of a patient is closed with the clip 103 remaining inside of the cerebrum.
However, in such a clipping operation, the flow of blood in the cerebral artery 102 stops temporarily, even though it is merely a short period of time. Hence, during this period, the oxygen which is supplied to the cerebrum is running short. This shortage of oxygen may kill cerebral cells. In other words, it is known that it may cause so-called ischemic neuronal damage.
This has raised a demand for an apparatus which is capable of monitoring the balance of oxygen supply and oxygen demand in a cerebrum during the clipping operation, so that such ischemic neuronal damage can be kept under control.
In view of the above described disadvantages, it is an object of the present invention to provide a cerebral-ischemia supervisory monitor which is capable of monitoring the balance of oxygen supply and oxygen demand in a cerebrum during the clipping operation, and deciding whether it is proper or not.